1. Field of the Invention
The present invention relates to a magnetic tape cartridge having a cartridge case which contains a single tape reel on which a magnetic tape such as a data recording/data reproducing medium is wound.
2. Description of Related Art
Conventionally, there has been widely known a magnetic tape cartridge comprising a substantially rectangular cartridge case made up of two mating case shell halves, i.e. upper and lower case halves, and a single tape reel on which a magnetic tape such as a computer data recording/reproducing medium is wound and which is contained in the cartridge case. Access to the magnetic tape by a tape threading arm of an associated tape drive is provided by a leader pin attached to a leading end thereof, directly or through a leader tape. The leader pin is known in various forms including, for example, a dumbbell type leader pin which comprises a cylindrical bar with upper and lower end collars.
The dumbbell type leader pin such as described in JP2006-209887A is retained within the cartridge case with the upper and lower end collars received in a pair of leader pin sockets and urged by biasing means such a leaf spring, respectively, which are located adjacent to a tape egress/ingress opening in upper and lower case halves, respectively, when the magnetic tape cartridge is in no use or unloaded from the associated tape drive (during storage or delivery). That is, the leader pin is retained with its axis in parallel with a direction of the height of cartridge case. This type of leader pin is formed slightly shorter than a height of the tape egress/ingress opening for withdrawing from and drawing into the cartridge case through the tape egress/ingress opening. Therefore, a slight clearance is produced between the upper end collar of the leader pin and the leader pin socket of the upper case half and. Further, since the biasing leaf spring is mounted in a mounting groove formed in each of the upper and lower case halves, a clearance is produced between the biasing leaf spring and the bottom of the mounting groove after assembled to the cartridge case. These is clearance result in a difference between contact areas or depressing force of the leaf biasing leaf springs against the upper and lower end collars of the leader pin, respectively. In such a case, it is difficult for the leader pin to be safely and securely retained in place.
There has been known another type of magnetic tape cartridge such as described in JP2001-148179A which prevents upper and lower end collars of a leader pin from slipping out of the leader pin sockets. This socket has a recessed bottom or undercut adapted for sinking of the leader pin. The leader pin used in the magnetic tape cartridge has an end collar made thin so as to easily slip into the recessed bottom. This thin end color results in loose contact with the biasing leaf spring due to a decrease in contact area. Consequently, it is difficult for the leader pin to be safely and securely retained in place.